Within the framework of the present invention, rotation is understood to mean a maneuver of the aircraft, in particular of a transport aircraft, which brings about an increase in the angle of attitude during a takeoff phase. The present invention may also be applied to the following maneuvers: a go-around in the course of an approach phase or a flare-out during a landing phase.
It is known that such a system for aiding piloting can comprise:                a set of information sources, including an information source which determines a current attitude of the aircraft;        a calculation unit which is connected to said set of information sources; and        a head-up display device of HUD type which is connected to said calculation unit and which is able to present, on a display screen, superimposed with the environment seen in front of the aircraft, at least one attitude scale and a means of indication (aircraft reference) associated with said attitude scale and indicating said current attitude of the aircraft.        
It is known to present, moreover, on said display screen, a marker generally situated between +10° and +15° on the attitude scale, that the pilot will align with said aircraft reference so as to obtain, for example in the case of a rotation, the desired attitude at the end of rotation. This known way of providing information to the pilot has several drawbacks. In particular:                the zone of the corresponding attitude scale being situated outside the field of display when the aircraft exhibits a zero attitude, the pilot does not see said marker at the moment of the initiation of the rotation. This often induces an overshoot of the desired value of attitude, by reason of too fast a subsequent appearance of said marker in the field of display of the display screen;        the pilot is compelled to look at the top part of the display field so as to monitor the appearance of said marker, and this may cause him to neglect the holding of the trajectory of the aircraft on the center of the runway; and        the visual scan is hardly optimal. Specifically, the pilot first looks downward during rolling, then upward during the rotation, then again downward after the rotation (since he uses the speed vector and the guidance associated therewith during the initial climb).        